JP2017195301A - Epitaxial growth system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epitaxial growth system capable of improving accuracy of a conveying operation of a semiconductor wafer at temperatures ranging from 600°C or higher to 800°C or lower and manufacturing an epitaxial wafer improved in a flatness property by reducing a difference in the conveying operation of the semiconductor wafer between a room temperature and the temperatures ranging from 600°C or higher to 800°C or lower.SOLUTION: In an epitaxial growth system, a horizontal plane projection shape of a first through-hole 22 of a susceptor 20 is a circle, and a horizontal plane projection shape of a second through-hole 36 of an arm 34 is an ellipse of which the length direction is matched with an extension direction of the arm. The epitaxial growth system is characterized in that the ellipse includes the circle at a room temperature and any temperatures ranging from 600°C or higher to 800°C or lower on a horizontal plane on which the first through-hole of the susceptor and the second through-hole of the arm are projected.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an epitaxial growth apparatus for vapor-phase growing an epitaxial film on the surface of a semiconductor wafer.

  An epitaxial wafer is obtained by vapor-phase-growing an epitaxial film on the surface of a semiconductor wafer. For example, when crystal integrity is more required or a multilayer structure with different resistivity is required, an epitaxial silicon wafer is produced by vapor-phase growth (epitaxial growth) of a single crystal silicon thin film on a silicon wafer. To do.

  For manufacturing an epitaxial wafer, for example, a single wafer epitaxial growth apparatus is used. Here, a general single wafer epitaxial growth apparatus will be described with reference to FIG. As shown in FIG. 8, the epitaxial growth apparatus 300 includes a chamber 10 including an upper dome 11, a lower dome 12, and a dome mounting body 13, and the chamber 10 defines an epitaxial film forming chamber. The chamber 10 is provided with a gas supply port 15 and a gas discharge port 16 for supplying and discharging the reactive gas at positions opposite to the side surfaces thereof. On the other hand, a susceptor 20 on which the semiconductor wafer W is placed is disposed in the chamber 10. The susceptor 20 is supported by the susceptor support shaft 30 from below. The susceptor support shaft 30 includes a main column 32 and three arms 34 (one not shown) extending radially from the main column 32 at equal intervals, and three support pins 38 (one at the tip of the arm 34). One is not shown) and supports the outer periphery of the lower surface of the susceptor 20 by fitting. The susceptor 20 has three through holes (one is not shown), and the three arms 34 have one through hole. Lift pins 40 are inserted through the through holes of the arms 34 and the through holes of the susceptor 20. The lower end portion of the lift pin 40 is supported by the lifting shaft 50. When supporting the semiconductor wafer W carried into the chamber 10, placing the semiconductor wafer W on the susceptor 20, and carrying out the epitaxial wafer after vapor phase growth out of the chamber 10, the lift shaft 50 The lift pin 40 moves up and down while sliding with the through hole of the arm and the through hole of the susceptor, and the semiconductor wafer W is moved up and down at the upper end.

  In the single-wafer epitaxial growth apparatus as described above, a plurality of lift pins are installed independently, and a certain degree of clearance is provided in the through hole through which the lift pins are inserted so that the lift pins can be raised and lowered. It is common. In Patent Document 1, in such a single-wafer epitaxial growth apparatus, when a semiconductor wafer exists on the lift pins, wobbling occurs due to the load of the semiconductor wafer, and the wobbling causes the semiconductor wafer to be placed on the susceptor. Therefore, by connecting a plurality of lift pins with an auxiliary member, wobbling of the lift pins when raising and lowering the semiconductor wafer is suppressed compared to the case without the auxiliary member, and the mounting position of the semiconductor wafer is reduced. A technique for reducing the deviation is described.

JP 2014-220427 A

  In order to obtain an epitaxial wafer having excellent flatness characteristics by making the film thickness of the epitaxial film uniform, the main surface of the semiconductor wafer is kept parallel to the horizontal plane during the transfer operation of the semiconductor wafer. It is essential. For this purpose, it is desirable that the center axis of the lift pin is positioned parallel to the vertical direction during conveyance. Here, the materials of the susceptor, lift pins, and susceptor support shaft, which are semiconductor wafer transfer mechanisms, are limited in terms of heat resistance, cost, and function. For example, when quartz is used for the susceptor support shaft, the susceptor is used. It is common to use a member in which silicon carbide is coated on a carbon graphite substrate for the lift pins. In this case, since the thermal expansion coefficient of carbon graphite or silicon carbide is larger than the thermal expansion coefficient of quartz, in the temperature range of 600 ° C. or higher and 800 ° C. or lower which is the transfer temperature of the semiconductor wafer W, the through hole of the susceptor is room temperature. It moves relative to the through-hole of the arm relative to the time by thermal expansion outward in the radial direction of the susceptor. Along with this, the inclination of the center axis of the lift pin passing through the through hole of the susceptor and the through hole of the arm with respect to the vertical direction also changes between room temperature and 600 ° C. to 800 ° C. Considering these, the center axis of the lift pin is in the radial direction of the susceptor with respect to the vertical direction at room temperature so that the center axis of the lift pin is positioned parallel to the vertical direction at a temperature of 600 ° C. to 800 ° C. In general, it is designed to tilt inward. However, since the adjustment of the transfer operation of the semiconductor wafer can be performed only at room temperature, if the center axis of the lift pin is tilted inward in the radial direction of the susceptor with respect to the vertical direction at room temperature, it is 600 ° C. or more and 600 ° C. or more. The inclination with respect to the vertical direction of the center axis of the lift pin at the following temperatures is different. For this reason, the difference in the transfer operation of the semiconductor wafer between room temperature and a temperature of 600 ° C. or higher and 800 ° C. or lower becomes large. That is, even if the semiconductor wafer transfer operation is adjusted at room temperature under the condition that the central axis of the lift pins is inclined inward in the radial direction of the susceptor with respect to the vertical direction, at a temperature of 600 ° C. or higher and 800 ° C. or lower, Since the center axis of the lift pin is positioned parallel to the vertical direction due to thermal expansion of the semiconductor wafer, the semiconductor wafer transfer operation at a temperature of 600 ° C. or higher and 800 ° C. or lower deviates from the semiconductor wafer transfer operation at the time of adjustment at room temperature. It will be. Therefore, the transfer operation of the semiconductor wafer at a temperature of 600 ° C. or higher and 800 ° C. or lower is not always good. As a result, there has been a problem that the epitaxial film thickness becomes non-uniform and an epitaxial wafer excellent in flatness characteristics cannot be obtained.

  Further, in Patent Document 1, a plurality of lift pins are interconnected by auxiliary members from the viewpoint of suppressing lift pin wobble, but the difference in thermal expansion coefficient between room temperature and 600 ° C. or more and 800 ° C. or less with respect to the design of each member. Is not considered at all, and the lift pins are fixed by interconnection. For this reason, it has been found that the influence of the change in the size of each member due to the difference in thermal expansion coefficient on the transfer operation of the semiconductor wafer is greater than that in the case where no auxiliary member is provided.

  Therefore, in view of the above problems, the present invention reduces the difference in the semiconductor wafer transfer operation at room temperature and a temperature of 600 ° C. to 800 ° C., thereby improving the accuracy of the semiconductor wafer transfer operation at a temperature of 600 ° C. to 800 ° C. It is an object of the present invention to provide an epitaxial growth apparatus that can improve the thickness of the epitaxial wafer and can manufacture an epitaxial wafer excellent in flatness characteristics.

The gist configuration of the present invention for solving the above-described problems is as follows.
(1) An epitaxial growth apparatus for vapor-phase growing an epitaxial film on the surface of a semiconductor wafer,
A chamber;
A susceptor having three or more first through-holes and mounting the semiconductor wafer in the chamber;
A susceptor support shaft for supporting the susceptor from below,
A main pillar disposed below the center of the susceptor;
Three or more arms extending radially from the main pillar below the peripheral edge of the susceptor and having second through holes;
The same number of support pins as the number of the arms that directly support the susceptor at the tip of the arm;
A susceptor support shaft having
It has an upper end portion and a lower end portion, and is inserted into the first through hole of the susceptor and the second through hole of the arm, and supports the semiconductor wafer at the upper end portion by being vertically moved up and down. And three or more lift pins for attaching and detaching the semiconductor wafer to and from the susceptor,
A lifting shaft that lifts and lowers the lift pin while supporting the lower end of the lift pin;
Have
The horizontal projection shape of the first through hole of the susceptor is a circle, and the horizontal projection shape of the second through hole of the arm is an ellipse whose longitudinal direction matches the extending direction of the arm,
The ellipse includes the circle at any temperature of room temperature and 600 ° C. or more and 800 ° C. or less on a horizontal plane on which the first through hole of the susceptor and the second through hole of the arm are projected. Epitaxial growth equipment.

  (2) Of the clearances between the lift pin and the inner wall of the second through hole of the arm at room temperature, the clearance on the support pin side of the arm is larger than the clearance on the main column side of the arm (1 ) Epitaxial growth apparatus.

  (3) The epitaxial growth apparatus according to (2), wherein the clearance on the support pin side of the arm is 0.35 mm or more at room temperature.

  (4) The epitaxial growth apparatus according to (2) or (3), wherein the clearance on the support pin side of the arm is 1.0 mm or less at room temperature.

  (5) The clearance between the lift pin and the inner wall of the first through hole of the susceptor is 0.1 mm or more and 0.35 mm or less at room temperature, according to any one of (1) to (4) above. Epitaxial growth equipment.

  (6) The clearance between the lift pin and the inner wall of the second through hole of the arm at room temperature, wherein the clearance on the main column side of the arm is 0.1 mm or more and 0.35 mm or less (1) The epitaxial growth apparatus as described in any one of-(5).

  (7) At room temperature, the distance from the center of the susceptor to the inner end of the first through hole of the susceptor is equal to the distance from the central axis of the main pillar to the inner end of the second through hole of the arm. And the distance from the central axis of the main pillar to the outer end of the second through hole of the arm is longer than the distance from the center of the susceptor to the outer end of the first through hole of the susceptor, The epitaxial growth apparatus according to any one of (1) to (6).

  (8) At a temperature of 600 ° C. to 800 ° C., the distance from the center of the susceptor to the outer end of the first through hole of the susceptor and the center axis of the main pillar to the outside of the second through hole of the arm And the distance from the center of the susceptor to the inner end of the first through hole of the susceptor is from the central axis of the main pillar to the inner end of the second through hole of the arm. The epitaxial growth apparatus according to any one of (1) to (7), wherein the epitaxial growth apparatus is longer than the distance.

  (9) Any of the above (1) to (8), wherein the diameter of the first through hole coincides with the minor diameter of the second through hole at room temperature and at any one temperature of 600 ° C. to 800 ° C. The epitaxial growth apparatus as described in any one.

  According to the epitaxial growth apparatus of the present invention, the difference in the semiconductor wafer transfer operation at room temperature and a temperature of 600 ° C. to 800 ° C. can be reduced, so that the semiconductor wafer transfer operation at a temperature of 600 ° C. to 800 ° C. can be reduced. The accuracy can be improved, and an epitaxial wafer excellent in flatness characteristics can be manufactured.

It is a schematic diagram of the epitaxial growth apparatus 100 by one Embodiment of this invention, and shows the state in room temperature. It is a schematic diagram of the epitaxial growth apparatus 100 by one Embodiment of this invention, and shows the state in the temperature of 600 to 800 degreeC. (A) is an exploded perspective view of the susceptor 20, and (B) is an exploded perspective view of the susceptor support shaft 30. 4A is an exploded perspective view of the lift pin 40, and FIG. (A) is room temperature, (B) is the schematic diagram which showed the positional relationship of the susceptor 20, the susceptor support shaft 30, the lift pin 40, and the raising / lowering shaft 50 in the temperature of 600 to 800 degreeC. (A) at room temperature, (B) at a temperature of 600 ° C. to 800 ° C., the first through hole 22 of the susceptor 20, the second through hole 36 of the arm 34, and the lift pin 40 in one embodiment of the present invention. It is the horizontal sectional view which showed the positional relationship of the straight trunk | drum 44. (A) shows the positional relationship between the susceptor 20, the susceptor support shaft 30, the lift pin 40, and the lifting shaft 50 in the epitaxial growth apparatus 200 according to Comparative Example 1 at room temperature and (B) at a temperature of 600 ° C. to 800 ° C. It is a schematic diagram. It is the model of the conventional epitaxial growth apparatus 300, and shows the state in room temperature.

  With reference to FIGS. 1 and 2, an epitaxial growth apparatus 100 according to an embodiment of the present invention will be described. The susceptor 20, the susceptor support shaft 30, the lift pins 40, and the lifting shaft 50 included in the epitaxial growth apparatus 100 will be described with reference to FIGS. Furthermore, with reference to FIG. 5 and FIG. 6, the first through hole 22 and the second through hole 36 which are characteristic parts of one embodiment of the present invention will be described.

(Epitaxial growth equipment)
The epitaxial growth apparatus 100 shown in FIGS. 1 and 2 includes a chamber 10, a susceptor 20 shown in FIG. 3A, a susceptor support shaft 30 shown in FIG. 3B, and 3 shown in FIG. The lift pins 40A, 40B, 40C and the lifting shaft 50 shown in FIG.

(Chamber)
The chamber 10 includes an upper dome 11, a lower dome 12, and a dome mounting body 13, and the chamber 10 defines an epitaxial film forming chamber. The chamber 10 is provided with a gas supply port 15 and a gas discharge port 16 for supplying and discharging the reaction gas at positions opposite to the side surfaces thereof.

(Susceptor)
The susceptor 20 is a disk-shaped member on which the semiconductor wafer W is placed inside the chamber 10. Here, of the main surfaces of the susceptor 20, the main surface on the side where the semiconductor wafer W is placed is the upper surface of the susceptor 20, and the main surface on the opposite side is the lower surface of the susceptor 20. Referring also to FIG. 3A, the susceptor 20 has three first through holes 22A, 22B, and 22C that penetrate the susceptor 20 in the vertical direction at equal intervals of 120 ° in the circumferential direction. That is, openings of the first through holes 22A, 22B, and 22C are formed on the upper surface of the susceptor 20, and openings of the first through holes 22A, 22B, and 22C are formed on the lower surface of the susceptor 20. Has been. Lift pins 40A, 40B, and 40C, which will be described later, are inserted through the first through holes 22A, 22B, and 22C, respectively. Each first through hole is concentrically positioned in a back surface region having a radius of 50% or more of the semiconductor wafer. The susceptor 20 may be made of carbon graphite (graphite) as a base material and the surface thereof coated with silicon carbide (SiC: Vickers hardness 2,346 kgf / mm ² ). On the surface of the susceptor 20, a counterbore part (not shown) for accommodating and placing the semiconductor wafer W is formed.

(Susceptor support shaft)
The susceptor support shaft 30 supports the susceptor 20 from below in the chamber 10, and as shown in FIG. 3B, the main pillar 32, the three arms 34A, 34B, 34C, and the three Support pins 38A, 38B, 38C. The main pillar 32 is disposed below the center of the susceptor 20.

  The arms 34 </ b> A, 34 </ b> B, 34 </ b> C extend radially from the main pillar 32 below the peripheral edge of the susceptor 20. Here, the side where the susceptor 20 is located along the main pillar 32 is the upper side of the arms 34A, 34B, 34C, and the opposite side is the lower side of the arms 34A, 34B, 34C. As shown in FIG. 3B, the arms 34A, 34B, 34C have second through holes 36A, 36B, 36C penetrating along the main pillar 32 in the vertical direction of the arms 34A, 34B, 34C, respectively. In the present specification, the “periphery of the susceptor” means a region that is 80% or more outside the susceptor radius from the susceptor center. The support pins 38A, 38B, and 38C directly support the susceptor 20 at the tips of the arms 34A, 34B, and 34C. That is, the support pins 38 </ b> A, 38 </ b> B, and 38 </ b> C support the rear surface peripheral edge portion of the susceptor 20. The second through holes 36A, 36B, and 36C are respectively inserted with lift pins 40A, 40B, and 40C described later. The characteristic part of the present embodiment is the positional relationship between the first through holes 22A, 22B, 22C, the second through holes 36A, 36B, 36C, and the lift pins 40A, 40B, 40C. It will be described later.

The susceptor support shaft 30 is preferably made of quartz (Vickers hardness 1,103 kgf / mm ² ), and particularly preferably made of synthetic quartz. However, the tip portions of the support pins 38 </ b> A, 38 </ b> B, 38 </ b> C are preferably made of the same silicon carbide as the susceptor 20.

(Lift pin)
As shown in FIG. 4A, the lift pins 40A, 40B, and 40C are inserted into the first through holes 22A, 22B, and 22C of the susceptor 20 and the second through holes 36A, 36B, and 36C of the arms 34A, 34B, and 34C, respectively. Straight body portions 44A, 44B, 44C, upper end portions 42A, 42B, 42C having a diameter larger than the straight body portions 44A, 44B, 44C and the first through holes 22A, 22B, 22C, and lower end portions 46A, 46B. , 46C. The lift pins 40A, 40B, and 40C are inserted into the first through holes 22A, 22B, and 22C of the susceptor 20 and the second through holes 36A, 36B, and 36C of the arms 34A, 34B, and 34C, respectively. The lift pins 40A, 40B, and 40C are moved up and down by a lift shaft 50, which will be described later, so that the semiconductor wafer W (back surface region having a radius of 50% or more) is supported by the upper end portions 42A, 42B, and 42C. The wafer W can be attached to and detached from the susceptor 20. Details of this operation will be described later. The lift pins 40A, 40B, and 40C are generally formed by coating a carbon graphite base material with silicon carbide, similarly to the susceptor 20.

(Elevating shaft)
As shown in FIG. 4B, the elevating shaft 50 defines a hollow that accommodates the main column 32 of the susceptor support shaft 30, and the main column 52 of the elevating shaft that shares the rotation axis with the main column 32, and this The three columns 54A, 54B, 54C branch off at the tip of the main column 52 of the lifting shaft, and the lower ends 46A, 46B, 46C of the lift pins 40A, 40B, 40C at the tips of these columns 54A, 54B, 54C. Support each. The lifting shaft 50 is preferably made of quartz. When the elevating shaft 50 moves up and down along the main pillar 32 of the susceptor support shaft 30, the lift pins 40A, 40B, and 40C can be raised and lowered.

(Heating lamp)
The heating lamps 14 are disposed in the upper region and the lower region of the chamber 10, and generally, a halogen lamp or an infrared lamp that has a high temperature raising / lowering speed and excellent temperature controllability is used.

(Epitaxial wafer manufacturing procedure)
Next, a series of operations of carrying in the semiconductor wafer W into the chamber 10, vapor phase growth of the epitaxial film onto the semiconductor wafer W, and carrying out the manufactured epitaxial wafer out of the chamber 10 are shown in FIGS. 1 and 2. Will be described with reference to FIG.

  First, the inside of the chamber 10 is preheated to a temperature of 600 ° C. or higher and 800 ° C. or lower by the heating lamp 14. Thereafter, the semiconductor wafer W is carried into the chamber 10 by a transfer blade (not shown). Lift pins 40A, 40B, and 40C (40B not shown in FIGS. 1 and 2) move upward of the susceptor 20, and the upper end portions 42A, 42B, and 42C of the lift pins come into contact with the back surface of the semiconductor wafer W. The semiconductor wafer W is once supported by lift pins 40A, 40B, and 40C. The lift pins 40A, 40B, and 40C are moved upward and downward through the lift shaft 50 that supports the lower ends 46A, 46B, and 46C.

  Next, by raising the susceptor support shaft 30, the susceptor 20 is moved to the position of the semiconductor wafer W, and the semiconductor wafer W is placed on the susceptor 20. In this state, the upper end portions 42A, 42B, 42C of the lift pins 40A, 40B, 40C are accommodated in the first through holes 22A, 22B, 22C of the susceptor 20. Thereafter, the semiconductor wafer W is heated to a temperature of 1000 ° C. or higher by the heating lamp 14 while a reactive gas is supplied from the gas supply port 15 into the chamber 10 to vapor-phase grow an epitaxial film having a predetermined thickness. An epitaxial wafer is manufactured. During vapor phase growth, the susceptor support shaft 30 is rotated about the main column 32 as a rotation axis, thereby rotating the susceptor 20 and the semiconductor wafer W thereon.

  Thereafter, the susceptor 20 is lowered by lowering the susceptor support shaft 30. This lowering is performed until the lift pins 40A, 40B, 40C are supported by the lift shaft 50 and protrude from the susceptor 20, and the manufactured epitaxial wafer is supported by the lift pins 40A, 40B, 40C. Then, a carrier blade (not shown) is introduced into the chamber 10 and the lift pins 40A, 40B, 40C are lowered to place the epitaxial wafer on the carrier blade. Thus, the epitaxial wafer is transferred from the lift pins 40A, 40B, and 40C to the transfer blade. Thereafter, the epitaxial wafer is carried out of the chamber 10 together with the transfer blade.

  In such a series of operations, adjustment of the transfer operation of the semiconductor wafer W at a temperature of 600 ° C. or higher and 800 ° C. or lower is performed at room temperature. Specifically, after the heating unit such as the heating lamp 14 is removed, the semiconductor wafer W is transferred to a predetermined position with respect to the susceptor 20 at room temperature while visually confirming from above the upper dome 11. Adjust the blade transfer operation.

  In the present embodiment, the first through holes 22A, 22B, 22C of the susceptor 20 and the second through holes 36A, 36B, 36C of the arms 34A, 34B, 34C are as shown in FIGS. The horizontal plane projection shape of the first through holes 22A, 22B, 22C of the susceptor 20 is a circle, and the horizontal plane projection shape of the second through holes 36A, 36B, 36C of the arms 34A, 34B, 34C is the arm 34A in the longitudinal direction. , 34B, 34C in the horizontal plane on which the first through holes 22A, 22B, 22C of the susceptor 20 and the second through holes 36A, 36B, 36C of the arms 34A, 34B, 34C are projected. The ellipse is set so as to include the circle at room temperature and at any temperature between 600 ° C. and 800 ° C. Hereinafter, the technical significance of setting the positional relationship of the first through holes 22A, 22B, 22C, the second through holes 36A, 36B, 36C, and the lift pins 40A, 40B, 40C in this way will be described with reference to FIGS. Description will be made with reference to (B) as appropriate.

  In order to obtain an epitaxial film having excellent flatness characteristics, the central axes of the lift pins 40A, 40B, and 40C are obtained at a temperature of 600 ° C. or higher and 800 ° C. or lower when the semiconductor wafer W is transferred as shown in FIG. Is required to be positioned parallel to the vertical direction. Thereby, when the semiconductor wafer W is transported, a state in which the main surface of the semiconductor wafer W is parallel to the horizontal plane is maintained. Here, the adjustment of the transfer operation of the semiconductor wafer W at a temperature of 600 ° C. or higher and 800 ° C. or lower is performed at room temperature as described above. However, as shown in FIGS. 5A and 5B, the positions of the first through holes 22A, 22B, and 22C of the susceptor 20 at a temperature of 600 ° C. or more and 800 ° C. or less are based on the arms 34A and 34B at room temperature. , 34C change due to thermal expansion relative to the positions of the second through holes 36A, 36B, 36C. Therefore, the second through holes 36A, 36B, and 36C of the arms 34A, 34B, and 34C are configured as described above so that the second through holes 36A, 36B, and 36C of the arms 34A, 34B, and 34C can absorb the change due to the thermal expansion. With this setting, as shown in FIG. 5A, a state is realized in which the central axes of the lift pins 40A, 40B, and 40C are parallel to the vertical direction even at room temperature. Thereby, since the difference in the transfer operation of the semiconductor wafer W between room temperature and a temperature of 600 ° C. or higher and 800 ° C. or lower is reduced, the accuracy of the transfer operation of the semiconductor wafer at a temperature of 600 ° C. or higher and 800 ° C. or lower can be improved. .

  When quartz is used for the susceptor support shaft 30 and a member obtained by coating a carbon graphite base material with silicon carbide is used for the susceptor 20, the thermal expansion coefficient of carbon graphite or silicon carbide is larger than that of quartz. Therefore, as shown in FIG. 6B, at temperatures of 600 ° C. or higher and 800 ° C. or lower, the first through holes 22A, 22B, and 22C of the susceptor 20 are armed on the basis of the room temperature shown in FIG. The susceptor 20 moves radially outward X2 relative to the second through holes 36A, 36B, 36C of 34A, 34B, 34C. Therefore, as shown in FIG. 6A, of the clearances between the lift pins 40A, 40B, 40C and the inner walls of the second through holes 36A, 36B, 36C of the arms 34A, 34B, 34C at room temperature, the arms 34A, 34B 34C, the clearance d3 of the support pins 38A, 38B, 38C side Y2 is preferably larger than the clearance d2 of the main pillar 32 side Y1 of the arms 34A, 34B, 34C. As a result, as shown in FIGS. 5A and 5B, the center axes of the lift pins 40A, 40B, and 40C are positioned parallel to the vertical direction at both room temperature and 600 ° C. to 800 ° C. Therefore, the difference in the semiconductor wafer transfer operation between room temperature and a temperature of 600 ° C. to 800 ° C. is reduced. In consideration of the difference between the thermal expansion coefficient of carbon graphite or silicon carbide and the thermal expansion coefficient of quartz, the support pins 38A, 38B, and 38C side of the arms 34A, 34B, and 34C shown in FIG. It is more preferable that the clearance d3 of Y2 is 0.35 mm or more.

  Referring to FIG. 6A, it is preferable that the clearance d3 of the support pins 38A, 38B, and 38C side Y2 of the arms 34A, 34B, and 34C is 1.0 mm or less at room temperature. Further, at room temperature, the clearance d1 between the lift pins 40A, 40B, 40C and the inner walls of the first through holes 22A, 22B, 22C of the susceptor 20 is preferably 0.10 mm or more and 0.35 mm or less. Further, of the clearances between the lift pins 40A, 40B, 40C and the inner walls of the second through holes 36A, 36B, 36C of the arms 34A, 34B, 34C at room temperature, the clearances on the main column 32 side Y1 of the arms 34A, 34B, 34C. It is preferable that d2 is 0.10 mm or more and 0.35 mm or less. By providing the clearance as described above, the lifting pins are more stably moved up and down. Therefore, even if the lift pins are not interconnected and fixed, wobbling of the lift pins during the transfer operation of the semiconductor wafer W is suppressed. From the viewpoint of further suppressing the wobbling of the lift pins, a ring-shaped lift pin support portion having holes through which the lift pins are inserted may be provided on the back surface of the susceptor.

  6A, at room temperature, a distance L1 from the center O1 of the susceptor 20 to the inner ends of the first through holes 22A, 22B, 22C of the susceptor 20 and the central axis O2 of the main pillar 32 to the arms 34A, The distances L3 to the inner ends of the second through holes 36A, 36B, 36C of 34B, 34C coincide with each other, and the second through holes 36A, 36B, 34A, 34B, 34C of the arms 34A, 34B, 34C from the central axis O2 of the main pillar 32. The distance L4 to the outer end of 36C is preferably set to be longer than the distance L2 from the center O1 of the susceptor 20 to the outer ends of the first through holes 22A, 22B, 22C of the susceptor 20. Furthermore, referring to FIG. 6B, at a temperature of 600 ° C. or higher and 800 ° C. or lower, distance L2 ′ from the center O1 of susceptor 20 to the outer ends of first through holes 22A, 22B, 22C of susceptor 20 and the main The distance L4 ′ from the central axis O2 of the column 32 to the outer ends of the second through holes 36A, 36B, 36C of the arms 34A, 34B, 34C coincides, and the first penetration of the susceptor 20 from the center O1 of the susceptor 20 The distance L1 ′ to the inner ends of the holes 22A, 22B, and 22C is longer than the distance L3 ′ from the central axis O2 of the main column 32 to the inner ends of the second through holes 36A, 36B, and 36C of the arms 34A, 34B, and 34C. It is preferable to set so that By setting the positional relationship between the first through holes 22A, 22B, 22C of the susceptor 20 and the second through holes 36A, 36B, 36C of the arms 34A, 34B, 34C in this way, room temperature and 600 ° C. or more and 800 ° C. or less. At any of these temperatures, the state in which the central axes of the lift pins 40A, 40B, and 40C are parallel to the vertical direction is realized, and the wobbling of the lift pins 40A, 40B, and 40C can be reduced.

  As shown in FIGS. 6A and 6B, the first through holes 22A, 22B, and 22C of the susceptor 20 are armed due to the difference in thermal expansion coefficient between the material of the susceptor 20 and the material of the arms 34A, 34B, and 34C. It is not the direction perpendicular to the radial direction of the susceptor 20 but the radial direction of the susceptor 20 that moves relative to the second through holes 36A, 36B, and 36C of the 34A, 34B, and 34C. Therefore, from the viewpoint of further suppressing the wobbling of the lift pins 40A, 40B, and 40C in the direction perpendicular to the radial direction of the susceptor 20, the first through-holes are at room temperature and at any one temperature of 600 ° C to 800 ° C. It is preferable to match the diameters r1 and r1 ′ with the minor diameters r2 and r2 ′ of the second through holes.

  In the present embodiment, the example in which the three arms 34A, 34B, 34C are extended at equal intervals in the direction branching from the main pillar 32 is shown, but the present invention is not limited to this, and four or more arms are provided. You may make it branch.

(Invention Example 1)
First, using the epitaxial growth apparatus shown in FIGS. 1 to 6, the semiconductor wafer transfer operation was adjusted by the method described above at room temperature. Next, the semiconductor wafer was transported at 700 ° C. Then, the silicon epitaxial wafer was manufactured according to the procedure mentioned above. Here, a member obtained by coating a carbon graphite base material with silicon carbide was used as the susceptor. Quartz was used for the susceptor support shaft. Further, a boron-doped silicon wafer having a diameter of 300 mm was used as the substrate of the epitaxial wafer.

  In the manufacture of the epitaxial wafer, first, trichlorosilane gas as a source gas was supplied at a temperature of 1150 ° C., and silicon coating was applied to the surface of the susceptor. Next, the silicon wafer was introduced into the chamber and placed on the susceptor using lift pins. Subsequently, hydrogen gas was supplied at 1150 ° C. to perform hydrogen baking, and then an epitaxial silicon film was grown at 1150 ° C. by 4 μm to obtain an epitaxial silicon wafer. Here, trichlorosilane gas was used as the source gas, diborane gas was used as the dopant gas, and hydrogen gas was used as the carrier gas.

  Referring to FIG. 6A, the first through-hole of the susceptor is set so that the horizontal projection shape is a circle, and the second through-hole of the arm has the horizontal projection shape and the longitudinal direction is the extension of the arm. The ellipse was set to match the direction. At room temperature, the diameter r1 of the circle and the minor axis r2 of the ellipse shown in FIG. 6A were 4.0 mm, and the major axis R of the ellipse was 4.4 mm. Moreover, the cross section of the lift pin in the horizontal direction was circular, and the diameter was set to be 3.35 mm at room temperature. That is, at room temperature, the clearance d3 shown in FIG. 6A was 0.725 mm, and d1 and d2 were 0.325 mm. Further, regarding the positional relationship between the first through hole of the susceptor and the second through hole of the arm, L1 and L3 shown in FIG. 6A are 114.25 mm, L4 is 118.65 mm, L2 is 118.25 mm, Furthermore, L2 ′ and L4 ′ shown in FIG. 6B were 118.2 mm, L1 ′ was 114.65 mm, and L3 ′ was 114.3 mm.

(Invention Example 2)
An epitaxial growth apparatus having the same configuration as that of Invention Example 1 was provided except that a ring-shaped lift pin support portion having holes through which the lift pins were respectively inserted was provided on the back surface of the susceptor.

(Comparative Example 1)
Both the first through hole of the susceptor and the second through hole of the arm were set so that the horizontal projection shape was a circle. The diameter of each circle was 4.0 mm at room temperature. Further, regarding the positional relationship between the first through hole of the susceptor and the second through hole of the arm, the distance from the center of the susceptor to the center of the first through hole of the susceptor is 113.9 mm at the room temperature, and the central axis of the main column The distance from the center of the second through hole of the arm to 114.3 mm was set. That is, as shown in FIG. 7 (A), at room temperature, the center axis of the lift pin is inclined inward in the radial direction of the susceptor with respect to the vertical direction, and as shown in FIG. The temperature was set so that the center axis of the lift pin was parallel to the vertical direction.

(Evaluation method and results)
In each comparative example and invention example, the lift pin is moved up and down through the lift shaft, thereby carrying the silicon wafer onto the susceptor and carrying out the epitaxial growth 10 times, and after each carrying operation and epitaxial growth. , The amount of deviation between the center of the silicon wafer and the center of the susceptor and the flatness characteristics of the silicon epitaxial layer were measured. The flatness measurement was evaluated by measuring the thickness distribution (SFQR value) on the surface of the silicon epitaxial layer using an optical interference displacement meter (manufactured by KLA-Tencor, WaferSight). The measurement results are shown in Table 1. First, as for the amount of deviation, the invention examples 1 and 2 were able to reduce the amount of deviation compared to Comparative Example 1 after any transport operation and epitaxial growth. Further, the average value of the deviation amount of 10 times was 1.82 mm on average in Comparative Example 1, whereas it was 0.77 mm on average in Invention Example 1 and 0.41 mm on average in Invention Example 2. . Next, as for the flatness characteristics, the invention examples 1 and 2 were able to improve the flatness characteristics as compared with the comparative example 1 after any transport operation and after epitaxial growth. Further, the average value of the flatness characteristics of 10 times was 195 nm on average in Comparative Example 1, whereas it decreased to 98 nm on average in Invention Example 1 and 59 nm on average in Invention Example 2.

  According to the epitaxial growth apparatus of the present invention, the difference in the semiconductor wafer transfer operation at room temperature and a temperature of 600 ° C. to 800 ° C. can be reduced, so that the semiconductor wafer transfer operation at a temperature of 600 ° C. to 800 ° C. can be reduced. The accuracy can be improved, and an epitaxial wafer excellent in flatness characteristics can be manufactured.

DESCRIPTION OF SYMBOLS 100 Epitaxial growth apparatus 10 Chamber 11 Upper dome 12 Lower dome 13 Dome attachment body 14 Heating lamp 15 Gas supply port 16 Gas exhaust port 20 Susceptor 22A, 22B, 22C 1st through-hole 30 Susceptor support shaft 32 Main pillar 34A, 34B, 34C Arm 36A, 36B, 36C Second through hole 38A, 38B, 38C Support pin 40A, 40B, 40C Lift pin 42A, 42B, 42C Upper end (head)
44A, 44B, 44C Straight body portion 46A, 46B, 46C Lower end portion 50 Lift shaft 52 Main shaft of lift shaft 54A, 54B, 54C Column W Semiconductor wafer X1 Center side of susceptor X2 Radial outside of susceptor Y1 Main column side Y2 Arm Support pin side of

Claims (9)

An epitaxial growth apparatus for vapor-phase growing an epitaxial film on the surface of a semiconductor wafer,
A chamber;
A susceptor having three or more first through-holes and mounting the semiconductor wafer in the chamber;
A susceptor support shaft for supporting the susceptor from below,
A main pillar disposed below the center of the susceptor;
Three or more arms extending radially from the main pillar below the peripheral edge of the susceptor and having second through holes;
The same number of support pins as the number of the arms that directly support the susceptor at the tip of the arm;
A susceptor support shaft having
It has an upper end portion and a lower end portion, and is inserted into the first through hole of the susceptor and the second through hole of the arm, and supports the semiconductor wafer at the upper end portion by being vertically moved up and down. And three or more lift pins for attaching and detaching the semiconductor wafer to and from the susceptor,
A lifting shaft that lifts and lowers the lift pin while supporting the lower end of the lift pin;
Have
The horizontal projection shape of the first through hole of the susceptor is a circle, and the horizontal projection shape of the second through hole of the arm is an ellipse whose longitudinal direction matches the extending direction of the arm,
The ellipse includes the circle at any temperature of room temperature and 600 ° C. or more and 800 ° C. or less on a horizontal plane on which the first through hole of the susceptor and the second through hole of the arm are projected. Epitaxial growth equipment.   The clearance between the lift pin and the inner wall of the second through hole of the arm at room temperature, the clearance on the support pin side of the arm is larger than the clearance on the main column side of the arm. Epitaxial growth equipment.   The epitaxial growth apparatus according to claim 2, wherein the clearance on the support pin side of the arm is 0.35 mm or more at room temperature.   The epitaxial growth apparatus of Claim 2 or 3 whose clearance by the side of the support pin of the said arm is 1.0 mm or less at room temperature.   The epitaxial growth apparatus as described in any one of Claims 1-4 whose clearance between the said lift pin and the inner wall of the said 1st through-hole of the said susceptor is 0.1 mm or more and 0.35 mm or less at room temperature.   6. The clearance according to claim 1, wherein, of the clearance between the lift pin and the inner wall of the second through hole of the arm at room temperature, the clearance on the main pillar side of the arm is 0.1 mm or more and 0.35 mm or less. The epitaxial growth apparatus according to claim 1.   At room temperature, the distance from the center of the susceptor to the inner end of the first through hole of the susceptor matches the distance from the central axis of the main pillar to the inner end of the second through hole of the arm, and The distance from the central axis of the main pillar to the outer end of the second through hole of the arm is longer than the distance from the center of the susceptor to the outer end of the first through hole of the susceptor. The epitaxial growth apparatus as described in any one of 6.   At a temperature of 600 ° C. to 800 ° C., the distance from the center of the susceptor to the outer end of the first through hole of the susceptor and the center axis of the main pillar to the outer end of the second through hole of the arm And the distance from the center of the susceptor to the inner end of the first through hole of the susceptor is greater than the distance from the central axis of the main pillar to the inner end of the second through hole of the arm. The epitaxial growth apparatus according to claim 1, which is also long.   The room temperature according to any one of claims 1 to 8, wherein a diameter of the first through hole and a minor axis of the second through hole coincide with each other at room temperature and at a temperature not lower than 600 ° C and not higher than 800 ° C. Epitaxial growth equipment.